WASHINGTON (AP) -- Virginia Gov. Bob McDonnell said Friday he backed away from a bill requiring women to undergo an invasive procedure before receiving an abortion because he believed it might not have withstood legal scrutiny.

McDonnell, chairman of the Republican Governors Association, addressed the matter at a panel hosted by Politico. It was his first extensive comments since asking lawmakers this week to drop a bill that would have required women seeking abortions to submit to a vaginal ultrasound procedure. The bill drew sharp opposition from Democrats and women's groups and was lampooned on national late night comedy shows.

"I got legal advice from various people, including my attorney general, that these kinds of mandatory invasive requirements might run afoul of Fourth Amendment law," McDonnell said. The Fourth Amendment to the Constitution guards against unreasonable search and seizure.

"I support the bill. I still support the bill. That never forfeits a governor's rights to make amendments," McDonnell said, adding he had not initiated the legislation and that it was pushed by legislators instead.

The bill would have required women seeking an abortion to undergo a procedure in which a wand is inserted in the vagina to yield an image of the fetus. McDonnell supported the bill as it was originally written but asked lawmakers Wednesday to amend it to require noninvasive ultrasound instead.

Seven states have laws mandating some form of pre-abortion ultrasound exam. None of the other states explicitly require the transvaginal procedure, according to the Guttmacher Institute that researches abortion-related issues.

McDonnell, who has been mentioned as a possible vice presidential candidate in 2012 and potential future presidential contender, said he wasn't concerned that the controversy had dealt a setback to the anti-abortion movement or to his own political prospects.

"There's been so much misinformation on this. There has been so much undue attention," McDonnell said. "This is a strong pro-life bill."

McDonnell appeared on the panel with Maryland Gov. Martin O'Malley, the Democratic Governors Association chairman who is expected to sign legislation next week allowing gay marriage in his state. McDonnell reaffirmed his opposition to same sex nuptials.